FIG. 9 show one example of a conventional one-way clutch used for a torque converter or the like of an automobile. The one-way clutch shown in FIG. 9 comprises an outer race 50 press-fitted and secured to a stator 56 by spline-fitting or the like, an inner race 51, a plurality of sprags arranged between the inner and outer races 51 and 50, an outer cage 53 and an inner cage 54 for holding the sprags 52, a spring 55 for biasing the sprags 52 in one direction, and annular retainer 57 arranged on one side of the outer race 50 and secured to the stator 56, etc.
On one side of the outer race 50 is arranged the annular retainer 57 so as to close a space between the inner and outer races 51 and 50. This annular retainer 57 has an outside diameter larger than an inside diameter of the outer race 50 and an inside diameter smaller than an inside diameter of the inner race 51. This annular retainer 57 rotates relatively to the fixed inner race 51 and is sometimes moved axially by an axial load. For this reason, a thrust needle bearing 65 in contact with a torque converter fixing portion (not shown) is held on the outer surface of the annular retainer 57.
The annular retainer 57 is formed at an outer peripheral portion and an inner peripheral portion of an inner surface 57a thereof with shoulders 58 and 59, and an end of the outer race 50 and an end of the inner race 51 are respectively loosely fitted therein. With this, the inner surface 57a of the annular retainer 57 is positioned within the space between the inner and outer races 51 and 50. Further, a portion between the inner and outer races 50 and 51 on the opposite side where the retainer 57 is arranged is closed by an annular retainer 60 formed integrally as a part of the stator 56. The annular retainer 60 has an inside diameter smaller than the outside diameter of the inner race. The annular retainer 60 is formed at an inner peripheral portion of an inner surface 60a thereof with a shoulder 61, and an end of the inner race 51 is loosely fitted therein.
The inner race 51 is formed at the inner peripheral surface with a spline 64 fitted in a spline 63 formed in a tubular fixed shaft 62.
According to a further example of the conventional one-way clutch, annular retainers 77 and 78 secured to a stator 76 are arranged on opposite sides of an outer race 70 as shown in FIG. 10. On the opposite sides of the outer race 70 are arranged the annular retainers 77 and 78 having an outside diameter larger than an inside diameter of the outer race 70 and an inside diameter smaller than an outside diameter of the inner race 71 so as to close a space between the inner and outer races 71 and 70. A bearing in contact with an opposed torque converter fixing portion is held on the outer surface of the annular retainer.
The annular retainers 77 and 78 are formed at an outer peripheral end and an inner peripheral portion of inner surfaces 77a and 78a thereof with shoulders 79, 80, 81 and 82, respectively, and an end of the outer race 70 and an end of the inner race 71 are loosely fitted therein. With this, the inner surfaces 77a and 78a of the annular retainers 77 and 78 are positioned within the space between the inner and outer races 71 and 70. The retainers 77 and 78 are axially secured by snap rings 83 and 84 stopped at the stator 76.
In the former example, the inner race 51 is formed at the inner peripheral surface with the spline 64. However, since the inner race 51 is made of metal such as bearing steel, carbon steel, etc., the number of processing for the spline 64 increases. Further, the number of assembling parts of the one-way clutch to a housing of the stator 56 or the like is large.
For achieving the recent demand for the trend of spacesaving, light-weighting and the like for the torque converter and the like of an automobile, the one-way clutch used for the torque converter and the like has a tendency in which an axial space thereof is controlled. In the latter example, the annular retainers 77 and 78 made of aluminum serve to cope with axial locating of the one-way clutch and maintenance of a diametral clearance between the inner and outer races 71 and 70 so as to response to the demand for the space-saving. However, since the inner surfaces 77a and 78a of the annular retainers 77 and 78 are positioned within the space between the inner and outer races 71 and 70, the axial spacing between the inner surfaces 77a and 78a is small. Therefore, it is not possible to make the axial length of the cages 73 and 74 long. As a result, the axial length of the sprags 72 held by the cages 73 and 74 is short, making it difficult to have a sufficient torque capacity.